The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• ) as eluent to give the pure product for analysis. 7,8-Diethyl 4-methyl 2-benzyl-3-methyl-5-(4-nitrophenyl)-2-azabicyclo[4.2.0]octa-3,7-diene-4,7,8-tricarboxylate (5e): yellow solid, 36%; mp 161–163 °C; 1H NMR (400 MHz, CDCl3) δ 8.07–8.05 (m, 2H, ArH), 7.37–7.34 (m, 2H, ArH), 7.33–7.29 (m, 3H, ArH

• ): [M + H]+) calcd for C29H31N2O8, 535.2075; found, 535.2076. 4,5-Diethyl 3-methyl 1-benzyl-2-methyl-3a-(4-nitrophenyl)-1,3a,4,6a-tetrahydrocyclopenta[b]pyrrole-3,4,5-tricarboxylate (6e): yellow solid, 35%; mp 153–155 °C; 1H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 8.8 Hz, ArH), 7.45–7.37 (m, 5H, ArH), 7.30

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• [25] that ethyl 2-bromo-2'-nitrobenzoylacetate reacts with thiobenzamide to give not only the expected 4-(2-nitrophenyl)-2-phenylthiazole-5-carboxylate, but also the dimerization product of thiobenzamide – i.e., 3,5-diphenyl-1,2,4-thiadiazole (XV). Similar observations have been made with other

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• molecule 5b. In the crystal packing (Figure S66 in Supporting Information File 1), molecules 5e tend to approach π-donor DMAN and π-acceptor p-nitrophenyl fragments, and the shortest distance between the two molecules is 2.810 Å (Figure S67 in Supporting Information File 1). The alternation of the C–C bond

• lengths in the aryl rings of molecules 5d and 5e may indirectly indicate the conjugation of the π-donor fragment with the π-acceptor p-nitrophenyl or p-cyanophenyl fragments. The qr parameter, calculated according to equation [32] (Figure 6) and characterizing the quinoid character of the aryl ring, was

• )benzonitrile and N,N-dimethyl-4-((4-nitrophenyl)ethynyl)aniline in chloroform solution are 373 and 416 nm, respectively [35]. In the same time, λmax for 2-((4-nitrophenyl)ethynyl)-1,8-bis(dimethylamino)naphthalene is 474 nm [36]. The red shift observed in the spectrum of this compound as well as in the spectra

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• according to experimental literature with slight modification [20]. α-Glucosidase (0.05 U/mL) and substrate, p-nitrophenyl-α-ᴅ-glucopyronoside (p-NPG) (1 mM) were dissolved in 0.1 M sodium phosphate buffer (pH 6.9). Fifty μL of sample (1 mg/mL in 10% DMSO) and 50 μL of α-glucosidase were preincubated at 37

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

• Elenilson F. da Silva,
• Krist Helen Antunes Fernandes,
• Denise Diedrich,
• Jessica Gotardi,
• Marcia Silvana Freire Franco,
• Carlos Henrique Tomich de Paula da Silva,
• Ana Paula Duarte de Souza and
• Simone Cristina Baggio Gnoatto

Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161

• of a 1-(3-nitrophenyl)-1,2,3-triazol-4-yl substituent in the C-28 position of both compounds 7 and 8 (EC50 = 0.314 and 0.053 µM, respectively) increased their antiviral activity, compared to that of the scaffolds 1 and 2 (EC50 = 5.3 and 17.3 µM, respectively) and acetylated compounds 3 and 4 (EC50

• -triazole pharmacophore via click chemistry reaction catalyzed by copper. The introduction of a proper 1-(3-nitrophenyl)-1H-1,2,3-triazole substituent into triterpenes resulted in promising anti-RSV activity, compared to that of RBV, one of the few drugs available for treating RSV infections. Compound 8 was

Synthesis of meso-pyrrole-substituted corroles by condensation of 1,9-diformyldipyrromethanes with pyrrole

• Baris Temelli and
• Pinar Kapci

Beilstein J. Org. Chem. 2022, 18, 1403–1409, doi:10.3762/bjoc.18.145

• catalyze the reaction (Table 1, entries 19–22). With the best conditions in our hands (Table 1, entry 11), different diformylated dipyrromethanes were subjected to condensation reactions. Electron-withdrawing 4-chlorophenyl, pentafluorophenyl, and 4-nitrophenyl-substituted corrole compounds were isolated

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• were generally good to excellent throughout. The notable exception is the evident drop in the isolated yield in the case of substrates bearing a nitrophenyl group at position 1 (cf. compounds 10j and 10n). This lowering of the yield, however, likely has to do with the combination of the nitrophenyl

• substituent and an N-alkyl group (considering that N-aryl nitrophenyl-substituted compound 10o was obtained in a respectable 91% yield). The structures of compounds 10a–s were unequivocally confirmed by 1H and 13C NMR spectroscopy (paying a particular attention to the appearance of the C=N2 signal in the

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• -unsaturated ketoesters, such as (E)-ethyl 4-(4-nitrophenyl)-2-oxobut-3-enoate (17), afforded the corresponding 5-unsubstituted DHPM derivative 18 in good yield (entry 6, Table 1). Similarly, heteroaromatic aldehyde derived ketoester 21, also underwent the tandem reaction to give the corresponding 5

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• -phenylhydrazine in acetic acid that delivers methyl 2-(1-benzyl-3-(2-nitrophenyl)-1H-indol-2-yl)acetate in 55% yield. Keywords: anticancer; Fischer indole synthesis; Heck reaction; heterocyclic compounds; indolobenzazepines; latonduines; paullones; Introduction Indolobenzazepines are fused heterocyclic

• ]. The N-protected 3-(2-nitrophenyl)indole was considered an important intermediate in this synthetic route (Scheme 1). The second retrosynthetic pathway (b) involved cyclization at position 3 of the indole ring, with a halo-aryl precursor [24]. In this case N-protected indole-2-acetic acid was regarded

• as the key intermediate. The third pathway (c) was centered around a ring-closure reaction via lactam-bond formation from a precursor that contains a carboxylic ester in position 2 and an o-aniline moiety in position 3 of the indole ring by Fischer indole synthesis from methyl 4-(2-nitrophenyl)-3

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• then account for the isolation of the acetylated analogue 9. The photochemical pathway described here represents a formal oxidative olefin cleavage of vinylogous nitroaryl-modified amides and ethers. The pathway adds to the diversity of photochemical pathways known for 2-nitrophenyl systems, and the

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• , 67.32; H, 3.44; N, 6.83; found: C, 67.18; H, 3.06; N, 6.97. (E)-2-(((2-(4-Nitrophenyl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenol (3ea): Orange solid, yield 65%; mp 223–226 °C; 1H NMR (600 MHz, CDCl3) δ 12.85 (s, 1H, OH), 8.77 (s, 1H, CH=N), 8.41 (s, 4H, 4-NO2C6H4), 8.34 (d, J = 8.7 Hz, 1H, H

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• in a satisfactory yield. Thus, a series of these catalysts was screened. The best results in term of the yield (83%) and ee (90%) were obtained while using the catalyst having a p-nitrophenyl group on the other side of thiourea moiety in CCl4 in the presence of 4 Å molecular sieves (Table 16). The

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• the putative pyrrolizine product appears to be faster than the rate of cyclization of the enaminone. In particular, decomposition occurred during the attempted cyclization of the 2-nitrophenyl- and 2-iodophenylenaminones 15k and 15l even before all of the precursor had been consumed. In the 2-nitro

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• via intramolecular cyclization reaction of ketones 31, p-nitrophenyl azide (PNA, 32) and amino esters 33 has been described by Dehaen et al. The products were often obtained in good yield and in all cases with the retention of the configuration of the stereocenter. The reaction was carried out by

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• ) and cobaltocene (Cp2Co) in order to create charge-transfer complexes with the purpose of searching for efficient magnetic materials based on fullerenes. It can be seen in Scheme 16 that methanofullerene 52 was obtained from the initial, also para-substituted, ethyl diazo(4-nitrophenyl)acetate in 32

• nitrophenylfullerenes 48 and 50. Synthesis of conjugate 52 of C60 with ethyl diazo(4-nitrophenyl)acetate. Synthesis of fluoride-containing phenylmethanofullerenes 53–56. Synthesis of “bucky ligands” 57–60. The synthetic route to methanofullerene-based palladium–bisaminoaryl complex 62. Synthesis of N-containing

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• in terms of their experimental application. In this study, we describe solutions for these two issues, using a chemoenzymatic approach to synthesize different ferulate compounds. The overall synthetic routes towards commercially available 5-bromo-4-chloro-3-indolyl and 4-nitrophenyl 5-O-feruloyl-α-ʟ

• -bromo-4-chloro-3-indolyl and 4-nitrophenyl 5-O-feruloylated α-ʟ-arabinofuranosides 1a and 1b. Although these substrates are commercially available, their synthesis involves 7 or 8 steps [15][16][17]. This contributes to their rather high retail costs (e.g., as of July 29th, 2020, 2500 and 778 € per 100

• reasonably cheap 5-bromo-4-chloro-3-indolyl or 4-nitrophenyl α-ʟ-arabinofuranosides. This afforded the corresponding feruloylated derivatives 1a and 1b (Figure 1). The yields (73 and 86% for the indolyl and 4-nitrophenyl derivatives, respectively) characterizing the regioselective enzymatic feruloylation of

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• under optimized conditions to extend the substrate scope. Firstly 2,4,6-collidine (1b) was successfully reacted for 48 h to obtain the successive product 5b in 87% yield (Table 3, entry 1). Next, 2-ethylpyridine (1c) was made to react under standard reaction conditions. To our surprise, 1-(4-nitrophenyl

• different catalysts. Synthesis of azaarene derivatives from different precursors. Our work: catalyst- and solvent-free benzylic addition of aldehydes to azaarenes. Large-scale experiments for the synthesis of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (3a) from 2,6-dimethylpyridine (1a) and 4

• -nitrobenzaldehyde (2a). Plausible mechanism for the formation of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (3a) under standard reaction conditions from 2,6-dimethylpyridine (1a) and 4-nitrobenzaldehyde (2a). Optimization of the reaction conditions.a Variation of the aldehyde component 2.a Variation of

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• atmosphere (5 atm) in an autoclave at room temperature provided compound 6 in 91% yield. The starting compound 5 was then reacted with commercially available isocyanates comprising p-nitrophenyl isocyanate, p-n-butylphenyl isocyanate, (S)-α-methylbenzyl isocyanate, and (R)-α-methylbenzyl isocyanate. The

• presence of p-nitrophenyl groups. At the same time, the singlets at 8.36 and 9.37 ppm reflected the ureido NH protons (DMSO-d6, 400 MHz, 298 K). The structures of the selected receptors 7a and 7d were further proven by single crystal X-ray studies. The calixarene 7a crystallised in a monoclinic system

• -nitrophenyl moieties, exhibiting several close CAr···CAr contacts at a 3.373 Å distance (Figure 3b). The receptor 7d crystallised in a triclinic system, space group P1, as a 1:3 complex with acetone (used as solvent for crystallisation). The main packing motive (see Figure 4) was represented by an infinite

Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

• Vladimir Ilkin,
• Vera Berseneva,
• Tetyana Beryozkina,
• Tatiana Glukhareva,
• Lidia Dianova,
• Wim Dehaen,
• Eugenia Seliverstova and
• Vasiliy Bakulev

Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243

• compound 1e and the product of its rearrangement to 5-(4-nitrophenyl)aminotriazole 1j [54], when the reaction was carried out in n-butanol at 105 °C (Table 2). Therefore, we can conclude that compound 3t was the product of a tandem reaction involving first the rearrangement of thioamide 1e to 1j followed

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• provide carbazoles covering a wide substrate and functional group spectrum [41]. Moreover, penta- and heptafused heteroacenes were prepared by the Cadogan reaction by annulation of nitrophenyl or nitrobenzothienyl precursors [42][43][44][45]. In this respect, we recently reported a Cadogan cyclization of

• ) in a similar low yield (16%) as before H-DTP (vide supra) (Scheme 3). The change of the reducing agent to triphenyl phosphite did not lead to a reaction at all. We turned then to related thienothiophene 18, which bears an o-nitrophenyl substituent instead of a 3-nitrothienyl residue in 16. 2-(2

• -Nitrophenyl)thieno[3,2-b]thiophene (18) was similarly prepared by Pd-catalyzed Stille-type reaction of monostannylated thienothiophene 14 and o-iodonitrobenzene (17) in 86% yield. Successive Cadogan cyclization of 18 with triethyl phosphite under reflux gave tetracyclic 9H-thieno[2’,3’:4,5]thieno[3,2-b]indole

Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• the reaction towards various substrates under the optimized conditions (Figure 2). Electron-deficient aryl iodides were well tolerated furnishing the corresponding trifluoromethylation products in high yields. Among the tested nitrophenyl derivatives, p- and o-nitrophenyliodide gave the products in

Microwave-assisted efficient one-pot synthesis of N²-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

• Moustafa Sherief Moustafa,
• Ramadan Ahmed Mekheimer,
• Saleh Mohammed Al-Mousawi,
• Mohamed Abd-Elmonem,
• Hesham El-Zorba,
• Afaf Mohamed Abdel Hameed,
• Tahany Mahmoud Mohamed and
• Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

• ), 8.65 (s, 1H), 10.94 (s, 1H), 11.29 (s, 1H); 13C NMR (150 MHz, DMSO-d6) δ 60.55, 127.39, 127.98, 130.30, 131.05, 131.42, 137.07, 154.52, 157.71, 158.04, 162.31; anal. calcd for C10H10ClN9: C, 41.17; H, 3.46; Cl, 12.15; N, 43.22; found: C, 41.30; H, 3.34; Cl, 12.30; N, 43.38. 6-(3-Nitrophenyl)-N2-(5H

Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells

• Giacomo Mari,
• Lucia De Crescentini,
• Serena Benedetti,
• Francesco Palma,
• Stefania Santeusanio and
• Fabio Mantellini

Beilstein J. Org. Chem. 2020, 16, 1606–1616, doi:10.3762/bjoc.16.133

• WST-8 [2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt] (Figure 5) and SRB (sulforhodamine B) (Figure 6) assays revealed that DHBER significantly reduced the cancer cell proliferation as compared to untreated cells both at 24 and 48 h of incubation

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• catalysts in a similar transformation [17]. In another study, Reiser and co-workers described a related allylation process of organic halides with allyltributyltin in the presence of [Cu(I)(dap)2]Cl as the catalyst [16]. This reaction was applied to a broad range of substrates, including a para-nitrophenyl

Room-temperature Pd/Ag direct arylation enabled by a radical pathway

• Amy L. Mayhugh and
• Christine K. Luscombe

Beilstein J. Org. Chem. 2020, 16, 384–390, doi:10.3762/bjoc.16.36

• incorporations of nitrobenzene into the polymer chains. The 2-nitrobenzoic acid used to form a silver carboxylate in the reaction system is the origin of the nitrophenyl group. Three different types of chains are represented, corresponding to incorporation of I/nitrophenyl, H/nitrophenyl, and two nitrophenyl end

• accounts for the formation of a carboxylate radical 11, explaining the presence of 2-nitrophenyl incorporation into the polymer chain. Additionally, this explains the formation of a phenyl radical at room temperature, and the poor control in which the nitrophenyl groups are incorporated into the chain

• Scheme 1. The region from 4–4.5 ppm indicates the interior indole repeat units compared with the terminal indole units. MALDI–TOF MS of PIn, indicating octylindole repeat units with three different types of end groups. These include 2-nitrophenyl, iodine, and hydrogen. A high yielding, highly selective